A projector for projecting images displays each image expressed by an input image signal in an expanded manner on a screen and is thus often used at presentations. The projector is generally constructed to project an image created by an image display device, such as a liquid crystal panel, on the screen via a projection lens.
In a conventional projector, a projection lens typically has a fixed zoom ratio, and a projection size on the screen is practically non-adjustable. One prior art technique adopted for adjustment of the projection size shifts the position of the projector and regulates the interval between the projector and the screen.
Another prior art technique uses a projection lens having the function of regulating a zoom ratio to optically adjust the projection size. The projection lens is, however, bulky and raises the total manufacturing cost.